Study On The Properties Of Triphenylene Discotic Liquid Crystal Derivatives Substituted By Diesters At 3 And 6 Positions

In this thesis,the triphenylene structure is used as the mesogen,and the 3,6-substituted diesterbased triphenylene derivatives with different side chain lengths,T5E36-3,T5E36-4,and T5E36-4,are prepared by organic synthesis.T5E36-5,T5E36-6and T5E36-7.Among them,T5 refers to the pentoxy triphenylene mesogen,E is used to refer to the ester chain connected to the triphenylene motif,3 and 6 refer to the 3,6 of the ester group on the triphenylene motif,The 6 substitution position,3,4,5,6,and 7respectively refer to the length of the saturated alkyl chain connected to the ester substitution position.The final product prepared by synthesis uses Fourier Infrared Spectroscopy(FT-IR),Proton Nuclear Magnetic Resonance Spectroscopy(1H-NMR)and High Resolution Mass Spectrometry(HR-MS)to confirm the chemical structure.Then use differential scanning calorimeter(DSC),polarizing microscope(POM)and onedimensional wide-angle X-ray diffraction(1D WAXD)to further study the liquid crystal properties of the synthesized compound.It is shown that only T5E36-3 is produced during the heating and cooling process.An endothermic or exothermic peak was found,and the remaining compound molecules all produced two peaks.Combined with the characterization results of POM,we determined that these series of molecules did not crystallize at room temperature.Therefore,we performed one-dimensional wide-angle Xray diffraction characterization of the compound.Through the analysis of the characterization results,we found that the diffraction peak of the alkyl chain split in the wide-angle region 2θ=15-20° at room temperature.Therefore,we believe that The molecules of this series tend to form a more ordered structure at room temperature.Then,we used two-dimensional wide-angle X-ray diffraction(2D WAXD)to perform further characterization and analysis.The characterization results showed that the three molecules of compound T5E36-3,T5E36-5,and T5E36-7 produced a series in the wideangle region.The diffraction pattern of the layer line structure is obtained by means of shear orientation.Therefore,it is determined that all three molecules can form a helical structure at room temperature.In addition,we also used Time-of-Flight to test the carrier mobility of several compounds at different temperatures(40°C and 150°C).The test results found that this series of molecules were at 40°C and 150°C.The carrier mobility at ℃ is higher than that at 150℃.